Distal Tibia: Is It The Best Source For Bone Graft?
Numerous primary and revisional surgical procedures mandate using either osseous autografts or allografts. Although allografts continue to increase in popularity, most podiatric surgeons will agree that autografts offer distinct advantages in healing and are preferable when possible. In comparison to autogenous grafts, allografts help facilitate an absence of donor site morbidity, unlimited supply and decreased surgical time. However, autografts provide numerous benefits such as host compatibility, viable precursor cells and superior immunologic properties.1,2
As with any surgical procedure, you must weigh the pros and cons of choosing auto- or allograft. You must also evaluate the patient and procedure in order to choose the appropriate site for graft harvesting. With this in mind, perhaps it’s time to consider (or reconsider) the distal medial tibia as a viable source for autogenous bone.
Indications or operative opportunities to employ autografts include delayed unions, non-unions, arthrodesis enhancement, tumors, repositional osteotomies and lengthenings. These are the more common indications for using an autograft. Post-traumatic reconstruction and reconstruction following osteomyelitis are two additional indications.
Reviewing The Pros And Cons Of Potential Donor Sites
In more than a century of formal autografting, researchers have advocated numerous harvest sites. Meador and Eggers provide a thorough manuscript illustrating the full history of auotgenous grafting.3
The illiac crest can give you a very large section of cancellous or corticocancellous bone. Depending upon the harvesting technique, surgeons may obtain one, two or three-sided grafts. Although the illiac crest is an excellent source for graft material, be aware that researchers have reported significant blood loss.4 Anecdotally, it has been my experience that this particular harvest site can be a significant source of post-operative pain when compared with podiatric donor sites.
Naturally, this also has the added inconvenience of having to have an alternative surgeon obtain the graft. Even though this graft is obtained from a relatively large osseous structure, keep in mind that complications, such as stress and complete fractures, are still possible.
The calcaneus is an excellent source of both cancellous and relatively small amounts of cortical bone.5 Depending on the position and size of the lateral incision(s), you can obtain various shapes and sizes of grafts. Make sure you avoid the sural nerve and also be extra cautious medially as there is a higher possibility of neurovascular injury or fibrous of the tarsal tunnel. As with any graft site, it is essential to take the appropriate precautions in order to avoid possible fracture following harvesting.
Primarily, the fibula provides a large cortical strut for operative procedures.6 Small portions of cancellous bone are available in the more distal aspects of the fibula. Your primary concern with this type of graft is not disrupting the ankle joint.7 This can occur if you inadverently enter the ankle joint or via aggressive resection of the fibula.
The proximal or distal tibia is a good source of fairly large quantities of corticocancellous bone. I harvest most autografts from the distal medial tibia for the following reasons: Ease of surgical access (few vital structures to avoid); minimal postoperative pain; low complication rate; and the choice of cortical or cancellous bone. Often, the medial column of the foot is the surgical site and due to external rotation of the limb, you’ll find the medial ankle more accessible than the lateral calcaneus.
Key Pearls For A Successful Procedure
Surgical technique varies from surgeon to surgeon, but articles by Saltrick, et. al., and Danzinger, et. al., clearly illustrate the technique for harvesting autografts from the distal medial tibia and the operative results.8,9
The first step is to determine the amount, type and shape of the graft that you will need. Cortical? Cancellous? Combination? Remember that cortical grafts provide more stability but cancellous grafts incorporate more quickly.
Appropriate incision placement not only reduces chances of neurovascular injury, but also reduces the chances of ankle joint injury. In the larger patient, anterior fluoroscopy of the ankle can make it easier to determine where you’ll make the incision. When you’re trying to make this determination with smaller patients, you can usually do so by palpating and identifying superficial anatomical landmarks.
Performing blunt dissection enables you to visualize the saphenous vein and nerve, which you can easily retract and avoid. You’ll find that dissection to the periosteum is typically quick and uncomplicated. You should avoid inadvertently dissecting posteriorly as this increases the possibility of medial neurovascular injury.
The periosteal incision is based upon the surgeon’s preference. Saltrick, et. al., describe an “I” incision.8 I’ve employed this same periosteal incision and found that it provides excellent exposure in both length and width of the graft site.
Once you’ve reflected the periosteum, outline the graft with either a sterile skin marker or a .062-inch K-wire. I initially drill the four main corners with K-wire and then complete the outline of the graft with repeated drilling.
Then I use a small osteotome to further clear the borders. You may use an oscillating saw instead, but be aware the increased temperature will often contribute to resorption (although minimal and probably negligable) of the graft margins. The deeper you drive the osteotome, the thicker the graft you’ll obtain. Then you would use a second osteotome to facilitate removal of the graft.
(As an aside, it is often necessary to angle anteriorly when completing the posterior section of the graft. This is due to the fact that the osteotome will easily deflect posteriorly and increase the chance of tendonous or neurovascular injury.)
Then you simply close the donor site in layer fashion, typically with a drain. Large grafts may require an onlay of allograft. You may also use bone wax to facilitate hemostasis.
Be Aware Of These Postoperative Considerations
Postoperative management will obviously depend upon the primary procedure you have performed. The majority of patients requiring autografts will be non-weightbearing for a considerable period after the procedure. This protects not only the recipient site, but the host site as well. (Any graft site can potentially form a stress riser.)
Saltrick, et. al., recommend a minimum of six weeks non-weightbearing following the harvesting of the graft.8 I have found this correlates well with the amount of complete offloading time that most patients have after the primary procedure.
A first metatarsal medial cuneiform arthrodesis is a prime example. Even when I’ve employed both internal and external fixation to facilitate early weightbearing, I will keep the patient off the affected side for six weeks to protect the tibia.
As an aside, if you allow the patient to use a removable walking boot during weightbearing, be aware that incision irritation can occur from the metal reinforcement or the straps on the device. You can reduce the irritation with adequate amounts of appropriate padding.
What About Potential Complications?
Even with appropriate planning and technique, you may encounter complications. Not only are there general complications (i.e. dehiscence, infection, painful scarring and nerve injury) inherent to all surgery, but there may also be complications (stress fracture or overt fracture) specific to donor sites.
In considering the medial distal tibia for a donor site, remember that where you harvest the graft from is important in reducing the chances of complications. Specifically, if you take the graft too inferiorly, be aware that a complete fracture of the medial malleolus may occur. Serial radiographs should include the donor site in addition to the host site. Fractures, either frank or stress, can occur with any graft site. The distal medial tibia is no exception. Regardless of the security of fixation for the recipient site, you must protect the graft site in order to avoid significant complications.
While the dissection for graft harvesting is uncomplicated, keep in mind that entrapment or injury of the saphenous nerve is possible. In my opinion, you can reduce this risk by using an ample incision to properly visualize structures and avoid excessive blunt injury.
Case Study One: Treating First Metatarsal Cuneiform Joint Pain
There are numerous opportunities for podiatric surgeons to employ autogenous grafting. Here are some case study examples.
A 53-year-old female came into our office nine months after being involved in a motor vehicle accident. Her chief complaint was pain at the level of the first metatarsal cuneiform joint with any type of weightbearing. The original injury was described as a dorsiflexion injury of the forefoot.
Radiographs revealed dislocation of the first metatarsal medial cuneiform joint with even minimal weightbearing. Due to the longstanding nature of the injury and resultant instability of the first ray, she had begun experiencing lesser metatarsalgia. Her symptoms correlated with the history and physical.
Eventually, the patient underwent a first metatarsal- medial cuneiform arthrodesis. We employed a corticocancellous graft from the distal medial tibia to not only enhance the fusion, but also to plantarflex and preserve the length of the first ray.
Many practitioners agree that when performing this Lapidus-type of procedure, grafting is often necessary. Appropriate shaping of the graft aids in the ease of positioning prior to fixation.
This particular patient had an uneventful postoperative course and we saw radiographic evidence of the graft incorporation eight weeks after surgery. She remains asymptomatic with no further breakdown of the midfoot. The donor site has also shown no complications.
Case Study Two: Using Cancellous Bone After Cyst Resection
A 31-year-old female came in to our office with left heel pain that had originally been treated as plantar fasciitis.
Radiographs and MRI revealed an intraossseous ganglion cyst within the body of the calcaneus. This patient underwent resection of the cyst through a cortical window within the lateral wall of the calcaneus. We removed a large portion of cancellous bone from the distal medial tibia to aid in filling the defect. Once we did this, we replaced the tibial cortical window.
This patient’s postoperative course was also uneventful. One year after the surgery, she showed no evidence of cyst recurrence. She did experience mild symptoms of neuritis associated with the harvest site, but we were able to manage the symptoms with conservative measures.
Case Study Three: How Corticocancellous Graft Played A Role In Treating Midfoot Degeneration
A 65-year-old male presented with a history of significant midfoot degeneration secondary to trauma.
There are multiple techniques that have been advocated for fusing this multiple joint complex. This patient, in particular, had bone loss and extensive destabilization from a prior aggressive exostectomy of the midfoot. Multiple joints were arthrodesed in the patient’s midfoot and these included the first and second metatarsal, their respective cuneiforms, the intercuneiform joints and the navicular cuneiform joints. In addtion to the degeneration, there was a significant sagittal plane deformity.
We obtained a large corticocancellous graft and used it to faciliate fusion, and reposition the medial column in a more plantarflexed position. Often, surgeons use cortical structs in this type of fusion to enhance stability (onlay grafting). You may use cancellous bone to fill defects left following cartilage resection. This is often needed in joints of the midfoot.
This is a good example of the versatility of this donor site. Large amounts of cortical and cancellous bone were available for the procedure. You can use cancellous bone to fill the defects and cortical bone for multiple onlays between joints. This particular patient has healed uneventfully with complete radiographic union at 13 weeks postoperatively.
As you can see, there may be some benefits for podiatric surgeons in considering the distal medial tibia as a source for autogenous bone. Despite the disadvantages of harvesting autogenous bone, this anatomic site provides ease of access; ample amounts and types of graft; and minimal complications for reconstruction of the foot and ankle.
Dr. Burks practices in Little Rock, Ark. He is a Diplomate of the American Board of Podiatric Surgery and is certified in both foot surgery and reconstructive rearfoot/ankle surgery.
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3. Meador, P.J., Eggers, C. The history of autogenous bone grafting. Ch.1 In Injury (supplement1), pp. S-A1-S-A4, 1994.
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